The history of this watch is related in "Chronometrophilia" N°25, Winter 1988, by Mr. Daniel Aubert, the own grand son of the maker. The instruction given by Capt § C°, the original drawings and calculations are also published. Among the several astronomical indications given by this watch, moonrise and moonset are certainly the most unusual features. According to the written correspondence between the firm Capt § C° and Mr. Leon Aubert, two possibilities were faced. The accuracy of the first one is far the best, giving a precision almost perfect after 1'000 years. It requires a 179 toothed wheel, revolving in 24 hours and driving a 148 toothed wheel. An other wheel of 135, set on the axis of the latter, drives the last wheel of the train with 169 teeth whose required revolution is 24 hours, 50 minutes and 30 seconds. The precision of the second way is less than one hour after 80 years, far good enough for such a watch, and much easier to perform. It requires a 64 toothed wheel, revolving in 24 hours and driving a wheel of 43, bearing another wheel of 37 teeth, driving the last wheel of the train with 57 teeth, whose revolution is performed in 24 hours, 50 minutes and 28'378 seconds. The dial has to be divided in 24 hours with a hand jumping forward 50 minutes and 30 seconds each time the moon is pas-sing at the meridian. This hand is set on a starwheel whose number of teeth has to be found : 24 hours = 86'400 seconds 50 minutes and 30 seconds = 3'030 seconds. 86'400/3'030 = 28,51 teeth. As a full number is required, a 57 teeth must be chosen. Therefore an extra wheel whose number of teeth has to be the double of the pinion bearing the hand, must be set on the starwheel. The passage of the moon at the meridian is then shown with a precision of -7 to +10 minutes (which re-presents the lunar equation of time). If moving the hand on the pinion, in order to indicate the moonrise time, the precision then would be of -27 to +24 minutes (ac-cording to the tables). It is possible to reduce the error by means of a spring loaded bascule set on the 57 toothed starwheel and acting on a cam. Revolving, the cam will push the bascule forward or backward. The 57 toothed starwheel being stopped by a spring loaded jumper, only the pinion bearing the hand is able to move the indications pointed by the hands are therefore adjusted. Still remains to be found the number of teeth of the starwheel bearing the cam. The sideral moon revolution is of 27 days, 7 hours, 43 minutes and 11,5 seconds. Divided by 24 hours, 50 minutes and 50 seconds, we get 26, 4 times. In order to use a full number, the starwheel must be of 5 x 26,4 = 132 teeth and the cam has to be made for sideral moon revolutions. However, according to the indications given by the tables, it seems that 26 is a number of teeth which fits perfectly. After 26 passages of the moon at the meridian, the same succession of errors is repeated with a few minute difference only. After several series, the mean error is never more than about 3 minutes. There-fore the cam has to be set on a starwheel of 26, driven by a pin set on a wheel whose revolution is performed in 24 hours, 50 minutes and 28,4 seconds. Owing to the small frictions which were neglected, the hand is inclined to jump too early, a spring loaded jumper must therefore be set on the 57 toothed starwheel. The moonset work can be built on the same principle. The outstanding craftsmanship of the movement is obvious on the pictures of the perpetual calendar work and of the equation of time and astronomical mechanism. Capt & C°, founded in 1875, successor to Capt & Mey-Ian, was run by Jules Cesar Capt. Previously the name of the firm was Nicole & Capt and was producing watches as early as 1845. It was founded by Adolph Nicole who settled in London with the same name.